User Manual

Table Of Contents

TRACER 4206 System Manual Section 2, Microwave Path Engineering Basics

Where, in the second equation the path loss has been lumped into a single quantity, L

, as discussed

previously. When using decibel notation, it is necessary that all quantities are individually converted to

decibels prior to performing addition and subtraction.

When d is expressed in miles and f in GHz, the path loss expression in decibels becomes

Figure 1 illustrates a wireless link containing all of the parameters previously discussed.

Figure 1. Example Microwave Path with Parameters

6. ANTENNA ALIGNMENT

With line-of-sight microwave communications, optimum system performance requires that the

transmitting and receiving antennas are properly aligned. This will ensure maximum received signal power

at each receiver. Antenna alignment must be achieved in both azimuth (along a horizontal plane) and

elevation (along a vertical plane). A received signal strength indicator (RSSI) is used to aid the equipment

installer in determining when alignment is maximized, by simply ensuring maximum RSSI. The RSSI

indicator for the TRACER 4106/4206 system is provided through the VT100 terminal menus accessed

through the RS-232 interface, and is presented as a series of bars indicating signal strength. More bars

means more RSSI, which ensures more received signal strength and better link performance.

If the local system has acquired a useful signal from the remote system, then the remote TRACER

4106/4206 RSSI can also be viewed from the local TRACER 4106/4206 VT100 terminal menu interface.

An RSSI Test point is also provided on the front panel. The voltage (relative to the gnd test point) present

on this test point represents a relative signal level of receive strength from the far end. The voltage at this

test point can vary from approximatly 0 to greater than 4 Volts DC, with 0 Volts corresponding to no signal

and 4 Volts or better to full signal strength.

Antenna Beam Patterns

Directly related to the subject of antenna alignment is the topic of antenna beam patterns. Antennas being

used with the TRACER 4106/4206 system will have a particular beam shape determined in part by the

physical construction and geometry of the antenna. The antenna beam patterns are characterized by a

dominant main lobe, which is the preferred lobe to use for point-to-point communications, and several side

96.6 20 log

d() 20·log

f()⋅

(dB)

d, L